The embodiments described herein relate generally to an electric machine, and more specifically, to a securing device associated with the electric machine.
An electric machine is typically in the form of an electric generator or an electric motor. The machine typically has a centrally located shaft that rotates relative to the machine. Electrical energy applied to coils within the motor initiates this relative motion which transfers the power to the shaft and, alternatively, mechanical energy from the relative motion of the generator excites electrical energy into the coils. For expediency the machine will be described hereinafter as a motor. It should be appreciated that a motor may operate as a generator and vice versa.
The shaft is supported within the motor by a bearing. The bearing is typically a separate component that is removeably secured to the motor. The bearing is typically secured to a housing of the motor to which other components of the motor are secured. The housing may be in the form of a plurality of components including an end portion, generally known as a motor end bell.
The bearing is typically secured in the housing or end bell by a fit to a bore within the end bell, a shoulder formed in the end bell and a securing device opposed to the shoulder. To permit assembly, the securing device includes an open bearing loading position and a closed bearing securing position. Such securing devices typically include fasteners, for example, a pair of opposed studs extending from the housing and a matched pair of protrusions or tabs that are rotatably secured to the studs, providing a first position in which they provide the bearing loading position and a second position in which they provide the bearing securing position. As the tabs rotate they must first pass the end face of the end bell and then the end face of the bearing.
Housings and housing components, including end bells are typically cast with the features as cast having dimensions that vary widely between castings. These wide variations in the as cast end face of the end bell make its location relative to the bearing end face vary widely, causing some assemblies to have the face of the end bell extend beyond the end face of the bearing, while other assemblies have the opposite relationship. These wide variations in dimensions may cause the tabs to interfere with end face of the end bell, in which case they will not rotate completely into the bearing securing position, providing no or incomplete securing of the bearing to the end bell. Further, these wide variations in dimensions may cause the outside diameter of the bearing to extend excessively outward, in which case the tabs will contact the outside diameter of the bearing and not the end face of the bearing, not providing compete securing of the bearing to the end bell. Such issues require great attention be given when assembling these components.